hi .
i have to find nozzle plume of a rocket in 3d simulation .
im not sure to use presssure farfield or pressure outlet for my computation domain and why ?

im using rng ke - density based - ideal gas . after about 100 iteration my solution diverges . i have checked boundary condition and viscous models many times but i could not find the problems .
mostly the error is floating point number error .
the inlet condition is 2800 kelvin and 140 bar .do you think its a supersonic flow ? and shock happens ?
i have attached a simplied picture of the model (the nozzle is cutted by an angle) .
do you have any idea what is wrong ??
thanks in advance .